1. Field of Invention:
This invention relates in general to the field of metal strip heat treating and processing. More particularly, the invention relates to means for guiding metal strip through various heat treating and cooling furnaces. Specifically, the invention relates to means for tensioning and guiding metal strip in a metal strip processing line.
2. Description of Related Art:
It is customary to tension metal strip prior to entering and after exiting an annealing furnace, such as disclosed in U.S. Pat. No. 3,385,946 to D. G. Hatchard. Pairs of two roll bridle sets are also used to stretch metal strip therebetween, as shown in U.S. Pat. No. 4,079,615, to O. F. Noe. The tension of metal strip may also be controlled by positioning tension rolls intermediate the sections of multi-section furnaces as shown in U.S. Pat. No. 4,371,332 to Matsuo et al. A variation of this idea is shown in U.S. Pat. No. 4,375,283 to Shimoyam which utilizes a master speed hearth roll positioned between a plurality of helper rolls both forwardly and rearwardly of the master speed hearth roll. The tensioning means in the above-noted prior art devices are concerned with tensioning metal strip in annealing furnaces, but none of these prior art devices relates to guiding metal strip just prior to exiting a strip processing line. Specifically, these prior art devices do not deal with the problems of utilizing a hot bridle to both tension and to guide metal strip during strip processing.
By way of example, in the hot dipping art, U.S. Pat. No. 4,519,337 to Ono et al. discloses a hot bridle downstream of the heat treatment furnaces and upstream of the metal coating means. This device utilizes motor-driven rolls to maintain differential strip tension upstream and downstream of the hot bridle. However, the hot bridle rolls are mounted in stationary bearing housings, thereby rendering the rolls incapable of instant adjustment to prevent the strip from drifting to either side of the rolls. The roll seals used by Ono et al. are also stationary, which further renders any quick strip guiding adjustment of the rolls very difficult, if not impossible. The Ono et al. hot bridle hood is integral with the coating line per se, as is conventional with prior art roll hoods positioned just upstream of the coating bath.